Cable driven joint actuator and method

Abstract

A cable driven actuator and actuator method involve a movable link that is movable about a path by a cable connected to the link, and a movable support member having a cable routing element. The support member is movable in a manner to change a moment arm of the cable acting on the link to control torque applied to the joint.

1 . A cable driven actuator, comprising a movable link that is moved about a path in response to a cable connected to the link, and a movable support member having a cable routing element disposed thereon wherein said support member is movable in a manner to change a moment arm of the cable acting on the link.  
     
     
         2 . The actuator of  claim 1  wherein the support member is rotatable to cause the cable routing element thereon to change the moment arm.  
     
     
         3 . The actuator of  claim 2  wherein the support member is rotatable about an axis that is coaxial with a pivot axis of the link.  
     
     
         4 . The actuator of  claim 1  wherein the support member moves in a translatable path to cause the cable routing element thereon to change the moment arm.  
     
     
         5 . The actuator of  claim 1  wherein the cable is substantially inelastic or elastic.  
     
     
         6 . A cable driven joint actuator comprising a pivotal link that is adapted to be operatively coupled to a joint to be actuated and that is pivoted about a pivot axis by a length of cable engaging a pulley on the link remote from the pivot axis and having an end coupled to the link, a pulley-support member having a cable positioning pulley and being rotatable by a motor about an axis that is coaxial with said pivot axis to cause the pulley to position the cable in a manner to change the moment arm of the cable acting on the link to control torque applied to the joint, and a device to maintain a substantially constant tension on the cable.  
     
     
         7 . The actuator of  claim 6  wherein the tensioner device comprises a cable spool and a second motor to rotate the spool.  
     
     
         8 . The actuator of  claim 6  wherein the tensioner device comprises a spring or bungee cord.  
     
     
         9 . The actuator of  claim 6  wherein said pulley of said link and said pulley of said pulley support member form a block and tackle to amplify torque applied to the joint.  
     
     
         10 . A cable driven actuator for human limb, comprising a cable connected to a human limb that comprises a pivotal link to be actuated and that is moved about a pivot axis by the cable, the cable being connected to the human limb remote from the pivot axis, and a movable support member having an axis generally centered on the pivot axis and having a cable routing element disposed thereon wherein said support member is movable in a manner to change a moment arm of the cable acting on the human limb to control torque applied to the joint.  
     
     
         11 . A robotic training or rehabilitating machine for a human user comprising the actuator of  claim 1  having a handle on the link for grasping by the user.  
     
     
         12 . A method of actuating a link, comprising providing a movable link that is movable about a path by a cable connected to the link and moving the link by moving a cable routing element in a manner to change a moment arm of the cable acting on the link.  
     
     
         13 . The method of  claim 12  including moving the cable routing element in a circular path.  
     
     
         14 . The method of  claim 12  wherein an axis of the circular path is coaxial with a pivot axis of the link.  
     
     
         15 . The method of  claim 12  including moving the cable routing element in a linear path.  
     
     
         16 . The method of  claim 12  wherein the movable link is a human limb.  
     
     
         17 . The method of  claim 12  wherein the movable link is a mechanical link.  
     
     
         18 . The method of  claim 12  where the cable routing element fixes an elastic cable to a pulley support member.